RC phase-shift oscillator, LM324
Oscillateurs   /    Oscillators
Électronique / Electronic

In this project, your are going to make an resistance-capacitance (RC) phase-shift oscillator using an RC network and OP amplifier.

With this circuit, you can easily generate low-frequency audio signals without using a resonator.

The OP amplifier comprises an inverting amplifier. Here, the input and output are 180 degrees out of phase with each other. The same phase shifting by 180 degrees occurs also in the phase-shift circuit made up with the RC network.

Specifically, the output attenuated in the RC network is amplified in the OP amplifier, which positively feeds the signal back to the RC network to generate oscillation. The oscillation is maintained because the gain in the OP amplifier is greater than the attenuation in the RC network.

When you finish wiring, turn power ON. Now you can hear a sound of approximately 1 kHz through the earphone.
The oscillating frequency is given as

in which R = R1 = R2 = R3, and C = C1 = C2 = C3.

However, the oscillating frequency in effect is approximately 1 kHz due to the influences of the wiring and the errors of resistance and capacitance.